阿摩線上測驗
15. Historians are still mystified by the question _____ some ancient civilizations disappeared suddenly in
history.
(A) that
(B) how
(C) is how
(D) that is
答案：登入後查看
統計： A(76), B(151), C(4), D(7), E(0) #908325
統計： A(76), B(151), C(4), D(7), E(0) #908325
